Surveillance of fetal lung lesions using the congenital pulmonary airway malformation volume ratio: Natural history and outcomes

Objectives: The congenital pulmonary airway malformation volume ratio (CVR) is a widely used sonographic measure of relative mass size in fetuses with lung malformations. The purposes of this study were to examine serial CVR measurements to understand longitudinal growth patterns and to determine correlation with postnatal imaging. Methods: An institutional review board-approved retrospective review was performed on fetuses referred for an echogenic lung malformation between 2002 and 2014. For each fetus, the CVR was prospectively calculated using 2D ultrasound and followed with advancing gestation. Results: Based on 40 fetuses, the mean initial CVR was 0.51±0.07 at 20.5±0.3weeks of gestation. The CVR increased after 24weeks of gestation (p=0.0014), peaking at a CVR of 0.96±0.11 at 25.5±0.05weeks, followed by a significant decrease in the CVR to 0.43±0.07 prior to term (p<0.0001). However, approximately one third showed no appreciable increase in size. The mean CVR was significantly correlated with postnatal chest computed tomography (CT) size dimensions (p=0.0032) and likelihood for lung resection (p=0.0055). Conclusions: Fetal lung malformations tend to follow one of two distinct growth patterns, characterized by either (1) a maximal CVR between 25 and 26weeks of gestation or (2) minimal change in relative growth. The mean CVR correlates with postnatal CT size and operative management.